Variable Interest Entities - Assets and Liabilities of Consolidated VIEs Prior to Consolidation (Detail) - USD ($) $ in Millions	Aug. 31, 2017	Nov. 30, 2016
Securitization Vehicles
Variable Interest Entity [Line Items]
Assets	$ 596.7	$ 837.7
Liabilities	595.5	837.2
Secured financing included in inventory and eliminated	49.2	57.6
Securitization Vehicles | Cash
Variable Interest Entity [Line Items]
Assets	5.2	16.1
Securitization Vehicles | Financial instruments owned
Variable Interest Entity [Line Items]
Assets	44.5	86.6
Securitization Vehicles | Securities purchased under agreement to resell
Variable Interest Entity [Line Items]
Assets	546.7	733.5
Securitization Vehicles | Fees, interest and other receivables
Variable Interest Entity [Line Items]
Assets	0.3	1.5
Securitization Vehicles | Other secured financings
Variable Interest Entity [Line Items]
Liabilities	590.7	813.1
Securitization Vehicles | Other liabilities
Variable Interest Entity [Line Items]
Liabilities	4.8	24.1
Other
Variable Interest Entity [Line Items]
Assets	1.4	1.3
Liabilities	0.2	0.2
Other | Cash
Variable Interest Entity [Line Items]
Assets	1.0	0.7
Other | Financial instruments owned
Variable Interest Entity [Line Items]
Assets	0.4	0.6
Other | Securities purchased under agreement to resell
Variable Interest Entity [Line Items]
Assets	0.0	0.0
Other | Fees, interest and other receivables
Variable Interest Entity [Line Items]
Assets	0.0	0.0
Other | Other secured financings
Variable Interest Entity [Line Items]
Liabilities	0.0	0.0
Other | Other liabilities
Variable Interest Entity [Line Items]
Liabilities	$ 0.2	$ 0.2